Thousands of exoplanets have been discovered since first they were seen in 1992, largely through observations made using NASA's Kepler Telescope.

Using these data, the team was able to measure the sizes of the planets transiting, or passing in front of, their host stars. In the past three years, Kepler has logged data from 287,309 stars - a number that climbs another 10,000 every few months. So how do astronomers sift through all that data?

New research using W.M. Keck Observatory on Maunakea has revealed consistent patterns regarding the shape and orbit of a group of exoplanets orbiting the same star. While one of the five planets (the one located closest to its star) is considered to be rocky, the other four exoplanets likely contain "large amounts of ice and gas".

And, they found, when there is some size variation in a planetary system, the planet closest to the star will be smaller, especially if the planet has a short orbital period - possibly because of photoevaporation.

The project that allowed citizen scientists to make the discovery is called Exoplanet Explorers, and is part of the popular citizen scientist platform Zooniverse.

If at least 10 users looked at any particular curve, and at least nine of them (90 percent) indicated a possible transit, Christiansen and Crossfield would analyze that specific signal further. Over 48 hours, the users made almost 2 million classifications from the available light curves.

It's called K2-138, where "K2" signifies that it was discovered by the Kepler Space Telescope during its K2 mission - an exoplanet-hunting mission that's been ongoing for the past three years.

An worldwide research team led by Université de Montréal astrophysicist Lauren Weiss discovered the pattern, which indicates that most planetary systems might have different formation histories than our own. No professional astronomer had yet looked through this dataset, called C12. Come on NASA, you're better than this. But Dr. Christian was confident that there are some more planets orbiting the distant sun-like star. The researchers believe Jupiter and Saturn had something to do with it. The signals appeared to resemble transits from five separate planets orbiting a single star, 190 parsecs, or 620 light years, away. There's no way water would exist on the surface, as portrayed here. It shows us yet another way that star systems can be configured.

After this decision, Barentsen left to get a cup of tea.

K2's data comprises light curves - graphs of light intensity from individual stars in the sky.

And that's exactly what they did - detecting a star with four planets orbiting around it.

"Some current theories suggest that planets form by a chaotic scattering of rock and gas and other material in the early stages of the planetary system's life", Christiansen said. The team scrambled to launch the effort, and over two days in April, as the program was broadcast live, Exoplanet Explorers drew 10,000 users who started sifting through the K2 data. They statistically validated the set of planet signals as being "extremely likely", according to Christiansen, to be signals from true planets. A fifth planet was also discovered on the same chain, with hints of a sixth as well.

The ensuing paper has been accepted for publication at The Astronomical Journal, but a pre-print can be found at arXiv. They hope to test how the presence or absence of Jupiter-like planets at large orbital distances relates to patterns in the inner planetary systems.

The findings indicate that most planetary systems may have formed differently than our own. "However, these theories are unlikely to result in such a closely packed, orderly system as K2-138", Christiansen said in a statement. "What's exciting is that we found this unusual system with the help of the general public".

According to the researchers, the citizen scientists across the world contributed immensely to the discovery of the five super-Earth exoplanets. Funding was provided by the NASA Science Mission Directorate, Google, the Alfred P. Sloan Foundation, NASA, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.